Weird dot

If the dot is not visible in a screenshot, you have a screen hardware issue that cannot be resolved through software or settings.

If the defect os bothersome, you would be best advised to visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to test and assess your iPad. If repair is required, you’ll be in the best possible place to explore your available options:

Genius Bar Reservation and Apple Support Options - Apple

Next time you see the dot, take a screenshot - then upload the screenshot here (redacted if necessary, using markup tools, to remove any personal or sensitive information).

With a better understanding of what you are seeing, contributors here will be better able to provide appropriate guidance.

Take a screenshot on your iPad - Apple Support

You can post your screenshot here using the image button of the message editing window:

Where is the green dot when it shows up? Is it near the front-facing camera?